The language for its designation is the abbreviation "Hz", in the English language the designation Hz is used for these purposes. At the same time, according to the rules of the SI system, if the abbreviated name of this unit is used, it follows with, and if the full name is used in the text, then with lowercase.

Origin of the term

The unit of frequency, adopted in the modern SI system, got its name in 1930, when the International Electrotechnical Commission adopted the corresponding decision. It was associated with the desire to perpetuate the memory of the famous German scientist Heinrich Hertz, who made a great contribution to the development of this science, in particular, in the field of electrodynamics research.

Term meaning

Hertz is used to measure the frequency of oscillations of any kind, so the scope of its use is very wide. So, for example, in the number of hertz it is customary to measure sound frequencies, the beating of the human heart, fluctuations in the electromagnetic field and other movements that repeat with a certain frequency. So, for example, the frequency of a human heart in a calm state is about 1 Hz.

Meaningfully, the unit in this dimension is interpreted as the number of vibrations made by the analyzed object during one second. In this case, experts say that the oscillation frequency is 1 hertz. Accordingly, a greater number of oscillations per second corresponds to a greater number of these units. Thus, from a formal point of view, the value denoted as hertz is the reciprocal of the second.

Significant frequencies are usually called high, insignificant - low. Examples of high and low frequencies are sound vibrations of varying intensity. So, for example, frequencies in the range from 16 to 70 Hz form the so-called bass, that is, very low sounds, and frequencies in the range from 0 to 16 Hz are completely indistinguishable to the human ear. The highest sounds that a person can hear lie in the range from 10 to 20 thousand hertz, and sounds with a higher frequency belong to the category of ultrasounds, that is, those that a person is not able to hear.

To designate large values ​​of frequencies, special prefixes are added to the designation "hertz", designed to make the use of this unit more convenient. Moreover, such prefixes are standard for the SI system, that is, they are used with other physical quantities. So, a thousand hertz is called "kilohertz", a million hertz - "megahertz", a billion hertz - "gigahertz".

The world is one and whole, and each part of it is a fragmentary reflection of everything in common in the small.

The frequency of 432 Hz is an alternative setting that is in line with the harmonics of the Universe.

Music based on 432 Hz has a beneficial healing energy because it is the pure tone of the mathematical basis of nature.

The archaic Egyptian instruments that have been discovered so far have mostly been tuned to 432 Hz.

In ancient Greece, musical instruments were predominantly tuned to 432 Hz. In the archaic Greek mysteries, Orpheus was the god of music, death and rebirth, as well as the guardian of Ambrosia and the music of transformation (his instruments were tuned to 432 Hz). And this is not accidental, the ancients knew more about the unity of the Universe than their contemporaries.

The current 440Hz based music setting is not in harmony on any level and does not match cosmic movement, rhythm or natural vibration.

When did the replacement of the frequency of 432 Hz by 440 Hz occur?

For the first time, an attempt to massively change the waves occurred in 1884, but thanks to the efforts of G. Verdi, they retained the previous system, after which they began to call the “La” = 432 Hz setting “Verdi system”.

Later, J.C. Deegen, a US Navy student of the physicist Hermann Helmholtz, persuaded the American Federation of Musicians at its annual meeting in 1910 to adopt A=440 Hz as the standard universal tuning for orchestras and bands. He was a professional in the field of astronomy, geology, chemistry, studied many branches of physics, especially the theory of light and sound. His opinion was fundamental in the study of musical acoustics. JK Deegen designed a 440 Hz military chime that was used for propaganda news during World War II.

Also, shortly before the Second World War, in 1936, the Minister of the Nazi movement and secret leader in mass control P. J. Goebbels revised the standard to 440 Hz - the frequency that most affects the human brain and can be used to control a large number of people and propaganda of Nazism. This was explained by the fact that if the human body is deprived of its natural tuning, and the natural tone is raised a little higher, then the brain will regularly receive irritation. In addition, people will stop developing, many mental deviations will appear, a person will begin to close in on himself, and it will become much easier to lead him. This was the main reason why the Nazis adopted the new frequency of the "A" note.

Around 1940 The US authorities introduced the 440 Hz tuning throughout the world, and finally, in 1953, it became the ISO 16 standard. The change from 432 Hz to 440 Hz is explained by: The Rockefeller Foundation's war on mind control by replacing and overlaying 440 Hz instead of the standard tuning.

440 Hz is an unnatural tuning standard, and music at 440 Hz conflicts with . The music industry is using the introduction of this frequency to influence the population to create more aggression, psycho-social agitation and emotional distress leading people to physical illness. Such music can also generate unhealthy effects or antisocial behavior, discord in the mind of a person.

The science of cymatics (the study of the visualization of sound and vibration) proves that frequency and vibration are the master keys and organizational basis for the creation of all matter and life on this planet. When sound waves travel on a physical medium (sand, air, water, etc.), the frequency of the waves is directly related to the formation of structures that sound waves create when they pass through a particular medium, such as the human body, which consists of more than 70% water!

Comparison of frequencies can be seen in the picture.

Special operation to change the classical frequency of music 432 to 440

What do we know about the note "La" 432 Hz? I think not so much, because 58 years have passed since the “International Organization for Standardization (ISO)” adopted the “A” 440 Hz system as the main one for the concert.

No one plays the 432 Hz tuning.

Baroque musicians prefer "A" - 415 Hz, which was most often used before the era of classicism. Modern musicians often use 440-442 Hz, and sometimes even higher, as the most familiar and comfortable tuning. But for a long period in musical history, it was the note “La” with a frequency of 432 Hz that was used.

Even after the adoption of the standard, in 1953, 23 thousand musicians from France held a referendum in support of the "Verdi" tuning of 432 Hertz, but were politely ignored. Where did “La” 440 Hz come from, and why exactly did it replace the similar note of 432 Hz that had existed for so long?

System 432 existed in ancient Greece, starting from Plato, Hippocrates, Aristotle, Pythagoras and other great thinkers and philosophers of antiquity, who, as you know, had invaluable knowledge about the healing effect of music on a person and cured many people with the power of music!

What note does the classical scale begin with? From the note “Do”, right!? So, the note “Do” in this system will be equal to 512 Hz, an octave below 256 Hz, even lower - 128-64-32-16-8-4-2-1. Those. the lowest note will be equal to one vibration per second, respectively, this is the first note of the scale!

The greatest violin maker of all time - Antonio Stradivari (whose secret of mastery of creating instruments has not yet been revealed), created his masterpieces in the 432 Hz tuning! The sound of the 432 is much quieter, warmer and closer. You feel it with all your heart.

Forbidden frequency 432 Hz

Despite the control established by the Illuminati since the days of Helmholtz and Nazi Goebbels regarding the replacement of the frequency 432 by 440, the musicians continue to play in an independent setting at the frequency 432. easier to control.

Goebbels knew that the frequency 432 had a perfect harmonic balance. This is the only frequency that evokes the Pythagorean musical spiral containing the famous and unsolved PLATO CODE.

True, recently the American mathematician and historian of science Jay Kennedy, who works at the University of Manchester in the UK, announced that he had cracked the secret code hidden in the works of the ancient Greek philosopher Plato. According to Kennedy, Plato shared the Pythagorean ideas about the music of the spheres - the inaudible musical harmony of the universe - and built his works according to the laws of musical harmony.

« One of the most famous Platonic dialogues, "The Republic", is divided into twelve parts, according to the number of sounds in the chromatic musical scale, which the ancient Greeks had ideas about. Moreover, at each junction there are phrases that in one way or another relate to music or sounds.', said the researcher.

What are the ancient solfeggio frequencies? These are the original sound frequencies used in ancient Gregorian chants such as the great hymn to St. John the Baptist. Many of them, according to church authorities, were lost many centuries ago.

These powerful frequencies were discovered by Dr. Joseph Puleo. This is described in the book Healing Codes for the Biological Apocalypse by Dr. Leonard Horowitz.

• Do - 396 Hz - Release from guilt and fear
• Re - 417 Hz - Neutralizing situations and promoting change
• Mi - 528 Hz - Transformation and miracles (DNA repair)
• Fa - 639 Hz - Connection and relationships
• Sol - 741 Hz - Awakening of Intuition
• La - 852 Hz - Return to the spiritual order.

The frequency 432 turns out to be 700 in an interesting way: PHI = 432.624 Or 24 hours x 60 minutes x 60 seconds = 864 | 000 864 / 2 = 432

The music surrounding us not only distracts our consciousness, but bypassing it is loaded directly into the subconscious, transforming the information hidden in it in such a way that people can be controlled.

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1 megahertz [MHz] = 1000000 hertz [Hz]

Initial value

Converted value

hertz exahertz petahertz terahertz gigahertz megahertz kilohertz hectohertz dekahertz decihertz centihertz millihertz microhertz nanohertz picohertz femtohertz attohertz cycles per second wavelength in exameters wavelength in petameters wavelength in terameters wavelength in gigameters wavelength in megameters wavelength in kilometers wavelength in hectometers wavelength in decameters wavelength in meters wavelength in decimeters wavelength in centimeters wavelength in millimeters wavelength in micrometers Compton electron wavelength Compton proton wavelength Compton neutron wavelength revolutions per second revolutions per minute revolutions per hour revolutions per day

More about frequency and wavelength

General information

Frequency

Frequency is a quantity that measures how often a particular periodic process is repeated. In physics, using frequency, the properties of wave processes are described. Wave frequency - the number of complete cycles of the wave process per unit of time. The SI unit of frequency is hertz (Hz). One hertz is equal to one oscillation per second.

Wavelength

There are many different types of waves in nature, from wind-driven sea waves to electromagnetic waves. The properties of electromagnetic waves depend on the wavelength. Such waves are divided into several types:

• gamma rays with a wavelength down to 0.01 nanometer (nm).
• X-rays with a wavelength - from 0.01 nm to 10 nm.
• Waves ultraviolet range, which have a length of 10 to 380 nm. They are not visible to the human eye.
• light in visible part of the spectrum with a wavelength of 380–700 nm.
• Invisible to people infrared radiation with a wavelength from 700 nm to 1 millimeter.
• Infrared waves are followed microwave, with a wavelength from 1 millimeter to 1 meter.
• The longest - radio waves. Their length starts from 1 meter.

This article is about electromagnetic radiation, and especially light. In it, we will discuss how wavelength and frequency affect light, including the visible spectrum, ultraviolet and infrared radiation.

Electromagnetic radiation

Electromagnetic radiation is energy, the properties of which are simultaneously similar to those of waves and particles. This feature is called wave-particle duality. Electromagnetic waves consist of a magnetic wave and an electric wave perpendicular to it.

The energy of electromagnetic radiation is the result of the movement of particles called photons. The higher the radiation frequency, the more active they are, and the more harm they can bring to the cells and tissues of living organisms. This is because the higher the frequency of the radiation, the more energy they carry. Greater energy allows them to change the molecular structure of the substances they act on. That is why ultraviolet, x-ray and gamma radiation is so harmful to animals and plants. A huge part of this radiation is in space. It is also present on Earth, despite the fact that the ozone layer of the atmosphere around the Earth blocks most of it.

Electromagnetic Radiation and Atmosphere

The earth's atmosphere transmits only electromagnetic radiation with a certain frequency. Most gamma rays, X-rays, ultraviolet light, some infrared radiation and long radio waves are blocked by the Earth's atmosphere. The atmosphere absorbs them and does not pass further. Part of electromagnetic waves, in particular, radiation in the short-wave range, is reflected from the ionosphere. All other radiation hits the Earth's surface. In the upper atmospheric layers, that is, farther from the Earth's surface, there is more radiation than in the lower layers. Therefore, the higher, the more dangerous it is for living organisms to be there without protective suits.

The atmosphere transmits a small amount of ultraviolet light to Earth, and it causes damage to the skin. It is because of ultraviolet rays that people burn in the sun and can even get skin cancer. On the other hand, some of the rays transmitted by the atmosphere are beneficial. For example, infrared rays that hit the surface of the Earth are used in astronomy - infrared telescopes monitor the infrared rays emitted by astronomical objects. The higher from the Earth's surface, the more infrared radiation, so telescopes are often installed on mountain tops and other elevations. Sometimes they are sent into space to improve the visibility of infrared rays.

Relationship between frequency and wavelength

Frequency and wavelength are inversely proportional to each other. This means that as the wavelength increases, the frequency decreases and vice versa. This is easy to imagine: if the oscillation frequency of the wave process is high, then the time between oscillations is much shorter than for waves whose oscillation frequency is lower. If you imagine a wave on a graph, then the distance between its peaks will be the smaller, the more oscillations it makes in a certain period of time.

To determine the speed of propagation of a wave in a medium, it is necessary to multiply the frequency of the wave by its length. Electromagnetic waves in vacuum always propagate at the same speed. This speed is known as the speed of light. It is equal to 299 792 458 meters per second.

Light

Visible light is electromagnetic waves with a frequency and length that determine its color.

Wavelength and color

The shortest wavelength of visible light is 380 nanometers. It is purple, followed by blue and cyan, then green, yellow, orange, and finally red. White light consists of all colors at once, that is, white objects reflect all colors. This can be seen with a prism. The light that enters it is refracted and lines up in a strip of colors in the same sequence as in a rainbow. This sequence is from the colors with the shortest wavelength to the longest. The dependence of the speed of propagation of light in a substance on the wavelength is called dispersion.

A rainbow is formed in a similar way. Water droplets dispersed in the atmosphere after rain behave like a prism and refract each wave. The colors of the rainbow are so important that in many languages ​​there is a mnemonic, that is, a technique for remembering the colors of the rainbow, so simple that even children can remember them. Many children who speak Russian know that "Every hunter wants to know where the pheasant is sitting." Some people invent their own mnemonics, and this is a particularly useful exercise for children, since by inventing their own method of remembering the colors of the rainbow, they will remember them faster.

The light to which the human eye is most sensitive is green, with a wavelength of 555 nm in bright environments and 505 nm in twilight and darkness. Not all animals can distinguish colors. In cats, for example, color vision is not developed. On the other hand, some animals see colors much better than humans. For example, some species see ultraviolet and infrared light.

reflection of light

The color of an object is determined by the wavelength of light reflected from its surface. White objects reflect all wavelengths of the visible spectrum, while black objects, on the contrary, absorb all waves and reflect nothing.

One of the natural materials with a high dispersion coefficient is diamond. Properly cut diamonds reflect light from both the outer and inner facets, refracting it like a prism. At the same time, it is important that most of this light is reflected upward, towards the eye, and not, for example, downward, into the frame, where it is not visible. Due to the high dispersion, diamonds shine very beautifully in the sun and under artificial lighting. Glass cut like a diamond also shines, but not as much. This is due to the fact that, due to the chemical composition, diamonds reflect light much better than glass. The angles used when cutting diamonds are of the utmost importance because angles that are too sharp or too obtuse either prevent light from reflecting off interior walls or reflect light into the setting, as shown in the illustration.

Spectroscopy

Spectral analysis or spectroscopy is sometimes used to determine the chemical composition of a substance. This method is especially good if the chemical analysis of the substance cannot be carried out by working with it directly, for example, when determining the chemical composition of stars. Knowing what kind of electromagnetic radiation a body absorbs, it is possible to determine what it consists of. Absorption spectroscopy, which is one of the branches of spectroscopy, determines which radiation is absorbed by the body. Such an analysis can be done at a distance, so it is often used in astronomy, as well as in working with poisonous and dangerous substances.

Determining the presence of electromagnetic radiation

Visible light, like all electromagnetic radiation, is energy. The more energy is emitted, the easier it is to measure this radiation. The amount of radiated energy decreases as the wavelength increases. Vision is possible precisely because people and animals recognize this energy and feel the difference between radiation with different wavelengths. Electromagnetic radiation of different lengths is perceived by the eye as different colors. Not only the eyes of animals and people work according to this principle, but also technologies created by people for processing electromagnetic radiation.

visible light

Humans and animals see a wide spectrum of electromagnetic radiation. Most people and animals, for example, respond to visible light, and some animals - also on ultraviolet and infrared rays. The ability to distinguish colors is not in all animals - some see only the difference between light and dark surfaces. Our brain defines color as follows: photons of electromagnetic radiation enter the eye on the retina and, passing through it, excite the cones, the photoreceptors of the eye. As a result, a signal is transmitted through the nervous system to the brain. In addition to cones, there are other photoreceptors in the eyes, rods, but they are not able to distinguish colors. Their purpose is to determine the brightness and strength of light.

There are usually several types of cones in the eye. Humans have three types, each of which absorbs photons of light within specific wavelengths. When they are absorbed, a chemical reaction occurs, as a result of which nerve impulses with information about the wavelength enter the brain. These signals are processed by the visual cortex of the brain. This is the area of ​​the brain responsible for the perception of sound. Each type of cone is responsible only for certain wavelengths, so to get a complete picture of the color, the information received from all the cones is added together.

Some animals have even more types of cones than humans. So, for example, in some species of fish and birds there are from four to five types. Interestingly, females of some animals have more cone types than males. Some birds, such as gulls that catch prey in or on the surface of the water, have yellow or red oil droplets inside their cones that act as a filter. This helps them see more colors. The eyes of reptiles are arranged in a similar way.

infrared light

Snakes, unlike humans, have not only visual receptors, but also sensitive organs that respond to infrared radiation. They absorb the energy of infrared rays, that is, they react to heat. Some devices, such as night vision goggles, also respond to the heat generated by the infrared emitter. Such devices are used by the military, as well as to ensure the security and protection of premises and territory. Animals that see infrared light, and devices that can recognize it, see not only objects that are in their field of vision at the moment, but also traces of objects, animals, or people who were there before, if not too much has passed. a lot of time. For example, snakes can see if rodents are digging a hole in the ground, and police officers who use night vision can see if traces of a crime have recently been hidden in the ground, such as money, drugs, or something else. Devices for detecting infrared radiation are used in telescopes, as well as for checking containers and chambers for leaks. With their help, the place of heat leakage is clearly visible. In medicine, infrared images are used for diagnosis. In the history of art - to determine what is depicted under the top layer of paint. Night vision devices are used to protect premises.

ultraviolet light

Some fish see ultraviolet light. Their eyes contain a pigment that is sensitive to ultraviolet rays. The skin of fish contains areas that reflect ultraviolet light, invisible to humans and other animals - which is often used in the animal kingdom to mark the sex of animals, as well as for social purposes. Some birds also see ultraviolet light. This skill is especially important during the mating season, when birds are looking for potential partners. The surfaces of some plants also reflect ultraviolet light well, and the ability to see it helps in finding food. In addition to fish and birds, some reptiles can see UV light, such as turtles, lizards, and green iguanas (pictured).

The human eye, like the eyes of animals, absorbs ultraviolet light but cannot process it. In humans, it destroys eye cells, especially in the cornea and lens. This, in turn, causes various diseases and even blindness. Even though ultraviolet light is harmful to vision, small amounts of it are needed by humans and animals to produce vitamin D. Ultraviolet radiation, like infrared, is used in many industries, for example, in medicine for disinfection, in astronomy for observing stars and other objects. and in chemistry for solidifying liquid substances, as well as for visualization, that is, to create diagrams of the distribution of substances in a certain space. With the help of ultraviolet light counterfeit banknotes and badges are detected if signs are to be printed on them with special inks recognizable by means of ultraviolet light. In the case of forged documents, the UV lamp does not always help, as criminals sometimes use the real document and replace the photo or other information on it, so that the markings for UV lamps remain. There are also many other uses for ultraviolet light.

color blindness

Due to visual defects, some people are unable to distinguish colors. This problem is called color blindness or color blindness, after the person who first described this feature of vision. Sometimes people can't see only colors at certain wavelengths, and sometimes they can't see colors at all. Often the cause is underdeveloped or damaged photoreceptors, but in some cases the problem is damage to the neural pathways, such as the visual cortex, where color information is processed. In many cases, this condition creates inconvenience and problems for people and animals, but sometimes the inability to distinguish colors, on the contrary, is an advantage. This is confirmed by the fact that, despite the long years of evolution, color vision is not developed in many animals. People and animals that are color blind can, for example, see well the camouflage of other animals.

Despite the benefits of color blindness, it is considered a problem in society, and the road to some professions is closed for people with color blindness. Usually they cannot get full rights to fly the aircraft without restrictions. In many countries, these people's licenses are also restricted, and in some cases they can't get a license at all. Therefore, they cannot always find a job where they need to drive a car, an airplane, and other vehicles. They also find it difficult to find a job where the ability to identify and use colors is of great importance. For example, it is difficult for them to become designers, or to work in an environment where color is used as a signal (for example, about danger).

Work is underway to create more favorable conditions for people with color blindness. For example, there are tables in which colors correspond to signs, and in some countries these signs are used in institutions and public places along with color. Some designers do not use or limit the use of color to communicate important information in their work. Instead of color, or along with it, they use brightness, text, and other ways of highlighting information so that even color blind people can fully capture the information conveyed by the designer. In most cases, people with color blindness do not distinguish between red and green, so designers sometimes replace the combination "red = danger, green = everything is fine" with red and blue. Most operating systems also allow you to adjust colors so that people with color blindness can see everything.

Color in machine vision

Machine vision in color is a rapidly growing branch of artificial intelligence. Until recently, most of the work in this area was done with monochrome images, but now more and more scientific laboratories are working with color. Some algorithms for working with monochrome images are also used for processing color images.

Application

Machine vision is used in a number of industries, such as controlling robots, self-driving cars, and unmanned aerial vehicles. It is useful in the field of security, for example, for identifying people and objects from photographs, for searching databases, for tracking the movement of objects, depending on their color, and so on. Locating moving objects allows the computer to determine the direction of a person's gaze or track the movement of cars, people, hands, and other objects.

To correctly identify unfamiliar objects, it is important to know about their shape and other properties, but color information is not so important. When working with familiar objects, color, on the contrary, helps to recognize them faster. Working with color is also convenient because color information can be obtained even from low-resolution images. Recognizing the shape of an object, as opposed to color, requires high resolution. Working with color instead of the shape of the subject allows you to reduce the processing time of the image, and uses less computer resources. Color helps to recognize objects of the same shape, and can also be used as a signal or a sign (for example, red is a danger signal). In this case, it is not necessary to recognize the shape of this sign, or the text written on it. There are many interesting examples of the use of color machine vision on the YouTube website.

Color Information Processing

The photos that the computer processes are either uploaded by users or taken with the built-in camera. The process of digital photography and video filming is well mastered, but the processing of these images, especially in color, is associated with many difficulties, many of which have not yet been resolved. This is due to the fact that color vision in humans and animals is very complex, and it is not easy to create computer vision like human one. Vision, like hearing, is based on adaptation to the environment. The perception of sound depends not only on the frequency, sound pressure and duration of the sound, but also on the presence or absence of other sounds in the environment. So it is with vision - the perception of color depends not only on the frequency and wavelength, but also on the characteristics of the environment. For example, the colors of surrounding objects affect our perception of color.

From an evolutionary point of view, such adaptation is necessary to help us get used to our environment and stop paying attention to insignificant elements, and direct our full attention to what is changing in the environment. This is necessary in order to more easily notice predators and find food. Sometimes optical illusions occur due to this adaptation. For example, depending on the color of the surrounding objects, we perceive the color of two bodies differently, even when they reflect light with the same wavelength. The illustration shows an example of such an optical illusion. The brown square at the top of the image (second row, second column) looks lighter than the brown square at the bottom of the image (fifth row, second column). In fact, their colors are the same. Even knowing this, we still perceive them as different colors. Since our perception of color is so complex, it is difficult for programmers to describe all these nuances in machine vision algorithms. Despite these difficulties, we have already achieved a lot in this area.

Unit Converter articles were edited and illustrated by Anatoly Zolotkov

Do you find it difficult to translate units of measurement from one language to another? Colleagues are ready to help you. Post a question to TCTerms and within a few minutes you will receive an answer.

Parameters whose values ​​are expressed in hertz can be found in the technical specifications of various devices: computer components, radios, measuring equipment - wherever alternating electrical signals flow. Nevertheless, not everyone can answer the question of what is measured in hertz without hesitation.

Hertz (Hz) is a derived SI unit used to express the frequency of periodic, that is, repeating after a certain period of time, processes. The numerical value of this value means the number of realizations of the specified process per second, which can be mathematically written as 1 Hz=1/s=s -1 . In hertz, you can quantify the frequency of phenomena of any physical nature, whether it is a change in the current in a household electrical network, contractions of the heart muscle, swing oscillations, the occurrence of impulses or the propagation of sound waves.

The easiest way to understand the meaning of the unit of measure in question is by the example of sinusoidal dependences of signals on time. The picture shows graphs of sound vibrations of different frequencies. In the first figure, for a period equal to a second, one maximum value of the wave occurs, and in the second - ten. That is, the appearance of the same states of process parameters in the latter case occurs ten times more often - with a frequency of 10 Hz.

Data transmission in communication systems, propagation of sound waves and many other processes can be characterized by frequencies several orders of magnitude greater than 1 Hz. Therefore, with this unit of measurement, standard SI prefixes are used, denoting multiples (1 kHz \u003d 10 3 Hz, 1 MHz \u003d 10 6 Hz and others).

In addition to the hertz, there is another unit of measurement that corresponds to 1 / s or s -1 - becquerel. Unlike the first one, which serves to describe periodic signals, this value characterizes the activity of sources of radioactive decay, which is a random process.

Here are some interesting facts on the topic of the article.

• The approximate frequency range of sounds audible to humans is from 20 Hz to 20 kHz. Moreover, with age, the upper limit shifts downward - most people gradually lose the ability to perceive high sounds.
• In Russia and European countries, the frequency of alternating current in power networks is 50 Hz, in the USA, Canada - 60 Hz, and in Japan, depending on the region, this network parameter can be equal to both 50 and 60 Hz.
• The heart of a healthy person who does not experience significant physical exertion beats at a frequency of approximately 1 Hz.
• The FM broadcasting range is from 87.5 to 108 MHz, the frequency of electromagnetic waves generated for cooking and heating food in a microwave oven is 2450 MHz.

Resonant frequency measurement method.

Frequency comparison method;

The discrete counting method is based on counting pulses of the required frequency for a specific period of time. It is most often used by digital frequency counters, and it is thanks to this simple method that fairly accurate data can be obtained.

You can learn more about AC frequency from the video:

The method of recharging a capacitor also does not involve complex calculations. In this case, the average value of the overcharge current is proportional to the frequency, and is measured using a magnetoelectric ammeter. The scale of the device, in this case, is graduated in Hertz.

The error of such frequency meters is within 2%, and therefore such measurements are quite suitable for domestic use.

The measurement method is based on electrical resonance that occurs in a circuit with adjustable elements. The frequency to be measured is determined by a special scale of the tuning mechanism itself.

This method gives a very low error, but only applies to frequencies above 50 kHz.

The frequency comparison method is used in oscilloscopes, and is based on mixing the reference frequency with the measured one. In this case, beats of a certain frequency occur. When these beats reaches zero, then the measured becomes equal to the reference. Further, according to the figure obtained on the screen, using the formulas, you can calculate the desired frequency of the electric current.

Another interesting video about AC frequency: